"Igualmente" means "likewise".
I am pleased to see you again = Estoy encantado de verte nuevamente.
Likewise = Igualmente.
"También" may mean "too" and "also".
He has time = Él tiene tiempo.
You too = Tú también.
I need a book and also a ruler = Necesito un libro y también una regla.
The negative of "también" is "tampoco".
I do not want that = Yo no quiero eso.
Neither do I = Yo tampoco.
He does not need the book nor the CD = Él no necesita el libro ni tampoco el CD.
Note: "ni" (sometimes translated as "nor") is a shortened version of "no y", literally "not and", use to deny a list of things.
She does not like coffee, nor tea, nor water, nor beer = A ella no le gusta ni el café, ni el té, ni el agua ni la cerveza.
I have used so many "nor" in English as an example of how "ni" is used in Spanish.
I hope I have not confused you with too much information. I hope this helps.